. >> one of the tensest weeks of the obama presidency, you had the bombing in massachusetts, at the boston marathon, and then not long after we were trying to grasp that, you had the ricin letters, one addressed to the president of the united states and another one addressed to senator roger wicker on capitol hill. ricin poisonous, that was entirely unconnected. of course, the explosion at the fertilizer plant outside of waco, texas, an extraordinary week. as it's unfolding you don't know if the events are connected or not. a very tense week. by the way, a thoroughly packed week politically. the president's big initiative on gun violence went down on capitol hill. >> let's get to pierre thomas, right now, our chief justice correspondent, we're learning a lot more about the suspects right now, pierre, and one of the points you have been making this morning is the way they handled themselves in the firefight suggests some kind of par military training. >> george, let's re-create what we think happened, firefight, they were throwing grenades or explosives out the car. the suspect who was kill